Majolino Domenico, Corsaro Carmelo, Crupi Vincenza, Venuti Valentina, Wanderlingh Ulderico
Department of Physics, University of Messina, C.da Papardo, S.ta Sperone 31, P.O. Box 55, 98166 S. Agata, Messina, Italy.
J Phys Chem B. 2008 Apr 3;112(13):3927-30. doi: 10.1021/jp711433d. Epub 2008 Mar 7.
By pulsed field gradient nuclear magnetic resonance measurements, we investigated the translational diffusion of water confined in the 200 A diameter pores of a sol-gel silica glass. The experiments, performed as a function of the hydration level, showed an enhancement of the self-diffusion coefficient when the water content corresponds to one or fewer monolayers. An explanation for this occurrence has been given in terms of a two-phase process involving a fast molecular exchange between the liquid and the vapor phase. Moreover, in partially filled pores, the surface water diffusion coefficient was measured, and was 4 times lower than the diffusion of liquid confined water in saturated spaces.
通过脉冲场梯度核磁共振测量，我们研究了限制在溶胶 - 凝胶二氧化硅玻璃直径为200埃孔隙中的水的平移扩散。实验作为水合水平的函数进行，结果表明当水含量相当于一个或更少单分子层时，自扩散系数会增强。这种现象已根据涉及液相和气相之间快速分子交换的两相过程给出了解释。此外，在部分填充的孔隙中，测量了表面水扩散系数，其比饱和空间中限制液体水的扩散系数低4倍。
